The new grape plant named ‘Improved Chancellor’ is of Vitis parentage, with the breeding chart tracing the lineage as shown in FIG. 3.
The new grapevine resulted from stably introducing a plant expressible tfdA gene from Ralstonia eutrophus into Chancellor grapes. The tdfA gene confers resistance in plants to the phenoxy herbicides, especially 2,4 D (2,4-diphenoxyacetic acid). For a general discussion, see U.S. Pat. Publication No. 2003-0154507. This resistance improves the performance of grapevines, which are by nature exquisitely sensitive to the phenoxy herbicides, with deleterious effects observed with drift of herbicide from fields in the area, especially grain fields sprayed to control broadleaf weeds. Damage from drift negatively affects growth and/or yield in affected vineyards.